GULLANE, Scotland (AP) — There's a reason why Brooks Koepka is the best young American golfer you've never heard of.

It has less to do with his game than his passport. The Florida native has collected four wins, but also 48 pages of government stamps and almost as many adventures in the last 10 months while playing in 11 different countries. His 2013 season-opening itinerary included India, South Africa and Kenya.

The extended road trip became part of a master plan Koepka hatched after missing the cut at last year's U.S. Open, then turning pro and failing to get through qualifying school for the PGA Tour. Like his friend and sometimes roommate Peter Uihlein, he pounced on the opportunity for four guaranteed starts on the Challenge Tour, the European tour's minor-league circuit. So much so that he and Uihlein have a running bet — whoever wins a tournament has to buy a jet ski for the house they share in Florida.

Koepka won for the first time last September in Spain, and instead of being flustered by language and culture, he decided to sample them and started ordering off the menu. He earned his European Tour card after winning three Challenge events already this year, and the mad dash that was necessary for Koepka to make it into this British Open pretty much encapsulates his brief pro career.

After capturing the Scottish Hydro Challenge near Inverness in late June, Koepka decided to try qualifying in London. The original plan was to drive all the way, but the car blew a tire late at night near Edinburgh. Koepka caught a few hours' sleep in a hotel, then a 6:30 a.m. flight to Heathrow Airport, arriving at Sunningdale Golf Club with just enough time to stretch. Even so, he shot 69-65 to take medalist's honors and book his place in the field here.

"The kid is impressive in lots of ways," said teaching pro Butch Harmon, whose son, Claude, works with Koepka when he's back home in Florida. "He's consistent. He's a fast learner, but he's smart enough not to try to do things on the golf course that he doesn't know how to do. Claude's been raving about his ball-striking for months.

"More impressive is the route he's taking. Lots of guys come out of college and if they don't get through Q-school, they take the most familiar path — the mini-tours back home. Over here," Harmon continued, "nearly every tournament is in a different country, with a different language. Just lining up visas can be a challenge. It shows a lot of maturity in a very short time."

You could say the same about the group Koepka joined for his practice round Tuesday. He and Dustin Johnson played Phil Mickelson and Rickie Fowler in what's generally acknowledged as the tour's most competitive — and expensive — pre-tournament round.

"That's another thing about him," said Harmon, who counts Johnson among his clients, has worked with Mickelson and tagged along with the group. "When they told Brooks the number (the ante for the match), he didn't flinch."

Whatever the number, it's in Mickelson's pocket now. The left-hander, who won last week at the Scottish Open, made a birdie putt at No. 14 to pull his side with one in the match-play game, and then upped his game to close the match out at the 17th.

"The chance to pick these guys' brains on how to get around courses like this — where to leave it, different ways to play the wind — is going to make me a better player down the road.

"So it was worth it," Koepka said. "Almost."

Either way, he made sure to get his money's worth. Koepka played his college golf at Florida State, but unlike Mickelson, he didn't set the golf world on fire as an amateur. On a family trip to the Masters some 15 years ago, the then-8-year-old chased Mickelson out to the parking lot hoping to get an autograph.

"He was in a hurry to get to his car," Koepka recalled. "He said, 'Catch me tomorrow.' I never got the autograph. Reminded him about that a couple of times since."

"We laughed about that today," Mickelson said sheepishly, then ticked off a handful of Koepka's shots from the round that stood out.

"His ball-striking is extremely solid," Mickelson summed up. "He's a wonderful putter. I can see why he earned his right to get on the European Tour so quickly."

Yet Koepka's ambitions hardly end there. He hopes to play regularly on both major tours, eventually earning the luxury of picking his spots the way Mickelson, Tiger Woods and a handful of golf's other big stars do.

"That's a long way off," Koepka said, "but it's been an interesting ride so far. I've seen more crazy weather in a few months than I'd seen before in my entire life.

"Some of the adventures have been good, some not so good. I miss my family and friends sometimes, and once or twice, I've been sick of playing golf.

"But if you're looking for a little bit of flavor to go with your game," he said, motioning over his shoulder at the scudding gray clouds rolling across Muirfield, "this is awfully tough to beat."

Mikko Lonen walks to his second shot at the fourth hole with King Arthurs Seat in the background during a practice round for the 2013 The Open Championship at Muirfield Golf Club.
Paul Cunningham USA TODAY Sports